Coatings having low emissivity and low solar reflectance

ABSTRACT

The invention provides low solar reflectance, low-emissivity coatings. The invention provides a monolithic pane bearing a low solar reflectance, low-emissivity coating. Further, the invention provides an insulating glass unit bearing a low solar reflectance, low-emissivity coating. Finally, the invention provides methods of producing coated substrates by depositing low solar reflectance, low-emissivity coatings.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. patent application Ser.No. 60/411,031 filed on Sep. 16, 2002, and U.S. patent application Ser.No. 60/376,826 filed on Apr. 29, 2002, the entire disclosure of each ofwhich is hereby incorporated by reference.

FIELD OF THE INVENTION

[0002] The present invention provides coatings for glass and othersubstrates. More particularly, this invention provides low-emissivitycoatings that have low solar reflectance. The invention also providesmethods of producing coated substrates by depositing coatings of thisnature, as well as insulating glass units and monolithic panes bearingthese coatings.

BACKGROUND OF THE INVENTION

[0003] Windows can reflect a surprising amount of solar radiation. Insome cases, this reflected radiation can become problematic. A certainamount of energy is, of course, carried in the solar radiation reflectedoff the exterior of a window. When this radiation falls on a nearbysurface, the surface can be discolored. While this can occur even with awindow having clear uncoated glass, the problem can be more significantwhen the window bears a coating that is highly reflective of solarradiation. This problem can also be more significant if the panes of thewindow in question have become inwardly cupped. (The panes of an IG unitcan become cupped, for example, during cold weather when gas in theinterior of the unit contracts.) The concave exterior pane of such awindow would concentrate its reflected radiation at a focal pointexterior to the window. This focal point would tend to move as the sunmoves across the sky, thus potentially leaving elongated paths ofdiscoloration.

[0004] As noted above, solar reflection problems can be particularlysignificant for windows and other glazings (e.g., doors, skylights,etc.) that bear reflective coatings, such as low-emissivity coatings.Low-emissivity coatings are well known in the present art. Thesecoatings commonly include one or more reflective silver layers and twoor more transparent dielectric layers. The silver layers in thesecoatings are highly reflective of infrared radiation. Thus, theyfavorably reduce the transmission of radiant heat through the coating.However, these coatings also tend to have relatively high solarreflectance. For example, a window bearing a conventional low-emissivitycoating would typically have a solar reflectance of at least about30%-35%, while the solar reflectance of a window having clear uncoatedglass would typically be around 13%. Thus, from the perspective of solarreflection problems, conventional low-emissivity coatings are less thanideal. Accordingly, it would be desirable to provide a low-emissivitycoating that has low solar reflectance.

[0005] It would be particularly desirable to provide a low-emissivitycoating that has low solar reflectance and also provides significantshading properties. As is well known, the solar heat gain coefficient(SHGC) of a window is the fraction of incident solar radiation that isadmitted through a window. There are a number of applications where lowsolar heat gain windows are of particular benefit. In warm climates, itis especially desirable to have low solar heat gain windows. Forexample, solar heat gain coefficients of about 0.4 and below aregenerally recommended for buildings in the southern United States.Similarly, any windows that are exposed to a lot of undesirable sunpreferably have a low solar heat gain coefficient. For example, windowson the east or west side of a building tend to get a lot of sun in themorning and afternoon. Likewise, sunrooms, solariums, and greenhousestypically get a great deal of sun. For applications like these, thesolar heat gain coefficient plays a vital role in maintaining acomfortable environment within the building in question. Thus, it isbeneficial to provide windows of this nature with coatings thatestablish a low solar heat gain coefficient (i.e., high shading abilitycoatings).

[0006] A tradeoff is sometimes made in high shading ability coatingswhereby the films selected to achieve a low SHGC have the effect ofrestricting the visible reflectance to a higher level than is desired.As a consequence, windows bearing these coatings may have a somewhatmirror-like appearance. It would be desirable to provide a high shadingability coating that has sufficiently low visible reflectance to obviatethis mirror-like appearance problem.

[0007] In addition to having undesirably high visible reflectance, thetransmitted and reflected colors of conventional high shading abilitycoatings tend not to be ideal. For example, these coatings commonlyexhibit hues that are more red and/or yellow than is desired. To theextent a coating has a colored appearance, it is pleasing if the coatingexhibits a transmitted and/or reflected hue that is blue or blue-green.The chroma of these coatings tends also to be greater than is desired.In most cases, it is preferable to provide a coating that is as colorneutral (i.e., colorless) as possible. Thus, the reflected andtransmitted colors of conventional low solar heat gain coatings tend tobe less than ideal, both in terms of hue and chroma.

[0008] U.S. patent application Ser. No. 60/376,826 (Hoffman), the entirecontents of which are incorporated herein by reference, disclosesadvantageous low-emissivity coatings that have low solar reflectance.These coatings achieve an exceptional combination of properties,including particularly low solar reflectance. In the '826 application,Hoffman describes five uniquely preferred low solar reflectance,low-emissivity film stacks. These film stacks are exceptionally wellsuited for a variety of applications. However, it would be desirable toimprove these film stacks in such a way that they impart greaterinsulating ability in windows. For example, it would be desirable toachieve substantial decreases in emissivity and U Value. Unfortunately,the changes required to decrease emissivity and U Value would beexpected to cause an attendant decrease in visible transmittance and/oran attendant worsening of reflected or transmitted color. As skilledartisans will appreciate, overcoming this problem is an exceedinglydifficult task, particularly considering the presence of the highabsorption primary layer in these coatings, which renders coating designhighly unpredictable.

SUMMARY OF THE INVENTION

[0009] In certain embodiments, the present invention provides a panebearing a low-emissivity coating. In these embodiments, thelow-emissivity coating comprises an infrared-reflective layer, a highabsorption primary layer, and a middle coat. The infrared-reflectivelayer comprises material that is highly reflective of infraredradiation. The infrared-reflective layer has a thickness of at leastabout 175 Å. The high absorption primary layer comprises material thatis highly absorptive of solar radiation. The high absorption primarylayer has a thickness of at least about 100 Å. The middle coat comprisesat least one transparent dielectric film and is positioned between theinfrared-reflective layer and the high absorption primary layer.

[0010] In certain embodiments, the invention provides a pane bearing alow-emissivity coating. In these embodiments, the low-emissivity coatingcomprises the following sequence of films (i.e., not necessarily in acontiguous sequence): an inner coat comprising at least one transparentdielectric film and having an optical thickness of between about 216 Åand about 312 Å; a high absorption primary layer comprising materialthat is highly absorptive of solar radiation and having a thickness ofleast about 100 Å; a middle coat comprising at least one transparentdielectric film and having an optical thickness of between about 600 Åand about 872 Å; an infrared-reflective layer comprising material thatis highly reflective of infrared radiation and having a thickness of atleast about 175 Å; a high absorption blocker layer comprising materialthat is highly absorptive of solar radiation and having a thickness ofat least about 45 Å; and an outer coat comprising at least onetransparent dielectric film and having an optical thickness of betweenabout 410 Å and about 582 Å.

[0011] In certain embodiments, the invention provides a method ofproducing coated substrates. The method comprises providing a panehaving generally-opposed first and second major surfaces. Upon one ofthe major surfaces, there is deposited a low-emissivity coatingcomprising an infrared-reflective layer, a high absorption primarylayer, and a middle coat. The infrared-reflective layer comprisesmaterial that is highly reflective of infrared radiation. Theinfrared-reflective layer has a thickness of at least about 175 Å. Thehigh absorption primary layer comprises material that is highlyabsorptive of solar radiation. The high absorption primary layer has athickness of at least about 100 Å. The middle coat comprises at leastone transparent dielectric film. The middle coat is positioned betweenthe infrared-reflective layer and the high absorption primary layer. Insome cases, the method comprises depositing the infrared-reflectivelayer as a silver-containing film. The method optionally comprisesdepositing the infrared-reflective layer at a thickness of between about182 Å and about 274 Å. In some cases, the method comprises depositingthe high absorption primary layer as a metallic film. The methodoptionally comprises depositing the high absorption primary layer as atitanium and/or niobium containing film. In some cases, the methodcomprises depositing the high absorption primary layer as a highlyabsorptive dielectric film. The method can optionally comprisedepositing the high absorption primary layer at a thickness of betweenabout 104 Å and about 151 Å. In some cases, the method comprisesdepositing the middle coat at an optical thickness of between about 600Å and about 872 Å. In some such cases, the method comprises depositingeach film of the middle coat as a film having a refractive index ofbetween about 1.7 and about 2.4. In some cases, the method comprisesdepositing the infrared-reflective layer further from the substrate thanthe high absorption primary layer. In some such cases, the methodfurther comprises depositing a high absorption blocker layer over theinfrared-reflective layer, the high absorption blocker layer comprisingmaterial that is highly absorptive of solar radiation and having athickness of at least about 45 Å. Optionally, the method can comprisesdepositing the high absorption blocker layer directly over theinfrared-reflective layer. In some cases, the method comprisesdepositing the high absorption blocker layer as a metallic film. Themethod can optionally comprise depositing the high absorption blockerlayer as a titanium and/or niobium containing film. The method canoptionally comprise depositing the high absorption blocker layer at athickness of between about 46 Å and about 78 Å. In some cases, themethod further comprises depositing an inner coat between the substrateand the high absorption primary layer, the inner coat comprising atleast one transparent dielectric film. The method can optionallycomprise depositing the inner coat at an optical thickness of betweenabout 216 Å and about 312 Å. For example, the method can comprisedepositing each film of the inner coat as a film having a refractiveindex of between about 1.7 and about 2.4. In some cases, the methodfurther comprises depositing an outer coat further from the substratethan the infrared-reflective layer, the outer coat comprising at leastone transparent dielectric film. In some such cases, the methodcomprises depositing the outer coat at an optical thickness of betweenabout 410 Å and about 582 Å. For example, the method can optionallycomprise depositing each film of the outer coat as a film having arefractive index of between about 1.7 and about 2.4.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012]FIG. 1 is a cross-sectional perspective view of an insulatingglass unit in accordance with certain embodiments of the presentinvention;

[0013]FIG. 2 is a schematic cross-sectional view of a low solarreflectance coating in accordance with certain embodiments theinvention;

[0014]FIG. 3 is a schematic side view of a sputtering chamber that hasutility in certain methods of the invention;

[0015]FIG. 4 is a schematic cross-sectional side view of a glazingcarrying a low solar reflectance coating in accordance with certainembodiments of the invention;

[0016]FIG. 4A is a detailed cross-sectional side view of region 4A ofthe low solar reflectance coating carried by the glazing of FIG. 4;

[0017]FIG. 5 is a perspective view of a glazing that carries a low solarreflectance coating and has been mounted in the outer wall of a buildingin accordance with certain embodiments the invention;

[0018]FIG. 6 is a graph of the glass-side solar reflectance of amonolithic pane carrying a low solar reflectance coating in accordancewith certain embodiments of the invention;

[0019]FIG. 7 is a graph of the transmitted color of an insulating glassunit carrying a low solar reflectance coating in accordance with certainembodiments of the invention;

[0020]FIG. 8 is a graph of the exterior reflected color of an insulatingglass unit carrying a low solar reflectance coating in accordance withcertain embodiments of the invention; and

[0021]FIG. 9 is a graph of the solar transmittance of a monolithic panecarrying a low solar reflectance coating in accordance with certainembodiments of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0022] The following detailed description is to be read with referenceto the drawings, in which like elements in different drawings have likereference numerals. The drawings, which are not necessarily to scale,depict selected embodiments and are not intended to limit the scope ofthe invention. Skilled artisans will recognize that the examplesprovided herein have many useful alternatives that fall within the scopeof the invention.

[0023] A variety of substrates are suitable for use in the presentinvention. In most cases, the substrate 10 is a sheet of transparentmaterial (i.e., a transparent sheet). However, the substrate 10 is notrequired to be transparent. For most applications, the substrate willcomprise a transparent or translucent material, such as glass or clearplastic. In many cases, the substrate 10 will be a glass pane. A varietyof known glass types can be used, and soda-lime glass is expected to bepreferred.

[0024] Tinted glass can optionally be used in certain embodiments of theinvention. Many suitable types of tinted glass are available from wellknown glass suppliers. Thus, a low solar reflectance coating of theinvention can be applied to a pane of tinted glass, if so desired. Insome cases, there is provided a multiple pane insulating glass unit (or“IG unit”) wherein the low solar reflectance coating is applied to apane of tinted glass, and this coated pane is incorporated (e.g., as anoutboard pane) into an IG unit that also includes at least one pane(e.g., an inboard pane) of clear glass. While embodiments of this natureare contemplated, the present low solar reflectance coating 40 isparticularly advantageous when used simply with clear glass.

[0025] In certain embodiments, the invention provides an IG unit that isprovided with at least one low solar reflectance coating. IG units arewell known in the present art. FIG. 1 depicts one example of an IG unit8 that can be provided in accordance with the invention. The invention,however, is not limited to practice with any particular type of IG unit.To the contrary, all aspects of the invention can be practiced with IGunits of any type (e.g., all-glass units, vacuum units, etc.). Thus, theillustrated IG unit type is not to be construed as limiting to theinvention. Further, while the term insulating “glass” unit is usedthroughout the present disclosure, it is to be understood that the panesneed not be formed of glass.

[0026] The IG unit 8 shown in FIG. 1 includes a first pane 10 and asecond pane 10′, together forming a pair of spaced-apart panes. Thepanes 10, 10′ bound a between-pane space 115 therebetween and anexterior space 250 thereabout. The panes have confronting inner surfaces14, 14′ oriented toward the between-pane space 115 and opposed outersurfaces 12, 12′ oriented away from the between-pane space 115. In theembodiment of FIG. 1, the panes 10, 10′ are held in a spaced-apartconfiguration (e.g., in a substantially parallel spaced-apartrelationship) by a spacer 101. The spacer 101 joins the peripheral innersurfaces of the panes. Thus, the spacer 101 and the confronting innersurfaces 14, 14′ of the panes 10, 10′ together define the between-panespace 115. Useful IG units, components thereof, and methods ofmanufacturing and using IG units are detailed in U.S. patent applicationSer. No. 10/076,211, the entire teachings of which are incorporatedherein by reference.

[0027] In the embodiment of FIG. 1, the illustrated IG unit 8 bears onlyone coating 40. However, other coatings can be provided on one or moreof the other major surfaces 12, 12′, 14′ of the IG unit 8, if sodesired. For example, it may be desirable to provide a variety ofdifferent coatings on one or both outer surfaces 12, 12′ of the IG unit.In certain embodiments, a hydrophilic coating (not shown) is provided onone or both outer surfaces 12, 12′. In one embodiment, the #1 surface ofan IG unit bears the hydrophilic coating, while the #2 surface bears thelow solar reflectance coating 40. Useful hydrophilic coatings aredisclosed in U.S. patent application Ser. Nos. 09/868,542, 09/572,766,and 09/599,301, the entire teachings of each of which are incorporatedherein by reference. In another embodiment, the #1 surface bears thehydrophobic coating, while the #2 surface bears the low solarreflectance coating 40. Useful hydrophobic coatings are disclosed inU.S. Pat. No. 5,424,130 (Nakanishi et al), the entire teachings of whichare incorporated herein by reference.

[0028] Further, certain embodiments provide an IG unit 8 wherein aphotocatalytic coating (not shown) is provided on one or both outersurfaces 12, 12′ of the IG unit 8. In one embodiment, the #1 surfacebears the photocatalytic coating, and the #2 surface bears the low solarreflectance coating 40. Useful photocatalytic coatings are described inU.S. Pat. Nos. 5,874,701 (Watanabe et al), 5,853,866 (Watanabe et al),5,961,843 (Hayakawa et al.), 6,139,803 (Watanabe et al), 6,191,062(Hayakawa et al.), 5,939,194 (Hashimoto et al.), 6,013,372 (Hayakawa etal.), 6,090,489 (Hayakawa et al.), 6,210,779 (Watanabe et al), 6,165,256(Hayakawa et al.), and 5,616,532 (Heller et al.), the entire teachingsof each of which are incorporated herein by reference.

[0029] The improved low solar reflectance, low-emissivity coating 40 ispreferably carried on the “second” surface of an IG unit. This isperhaps best appreciated with reference to FIGS. 4 and 5, wherein thereis illustrated an IG unit 8 mounted upon a frame 90 in an exterior wall98 of a building 99. In such embodiments, the “first” (or “#1”) surfaceis that which faces (i.e., is exposed to, and communicates with) theoutdoor environment. Accordingly, it is the #1 surface that radiation SRfrom the sun 77 first strikes. In FIGS. 4 and 5, the outer surface 12 ofthe first pane 10 is the so-called first surface. Moving from the #1surface toward the interior side 33′, the next surface is the “second”(or “#2”) surface. As seen in FIG. 4, the inner surface 14 of the firstpane 10 is the so-called second surface. Moving further toward theinterior side 33′, the next surface is the “third” (or “#3”) surface,followed by the “fourth” (or “#4”) surface. In FIG. 4, the inner surface14′ of the second pane 10′ is the so-called third surface, and the outersurface 12′ of the second pane 10′ is the so-called fourth surface.

[0030] Thus, certain preferred embodiments of the invention provide anIG unit wherein an inner surface bears the low solar reflectance,low-emissivity coating 40. The coating 40 includes aninfrared-reflective layer 150 and a high absorption primary layer 80.The high absorption primary layer 80 comprises titanium, niobium, oranother material that is highly absorptive of solar radiation (e.g., ahighly absorptive dielectric, such as titanium nitride). The highabsorption primary layer 80 desirably has a thickness of at least about100 Å, preferably between about 104 Å and about 151 Å, and morepreferably between about 110 Å and about 144 Å. The infrared-reflectivelayer 150 comprises silver or another electrically-conductive material(e.g., metal), such as gold, copper, or the like. Theinfrared-reflective layer 150 desirably has a thickness of at leastabout 175 Å, particularly preferably between about 182 Å and about 274Å, and more preferably between about 193 Å and about 262 Å. The highabsorption primary layer 80 is preferably positioned further to theexterior 77′ than the infrared-reflective layer 150, as is perhaps bestappreciated with reference to FIGS. 4 and 4A. Preferably, the highabsorption primary layer 80 is separated from the infrared-reflectivelayer by a middle coat 90 comprising at least one transparent dielectricfilm. Thus, certain embodiments provide a low solar reflectance,low-emissivity coating comprising: a high absorption primary layer(e.g., of the thickness and composition described in this paragraph); aninfrared-reflective layer (e.g., of the thickness and compositiondescribed in this paragraph); and a middle coat 90 comprising at leasttransparent dielectric layer positioned between the high absorptionprimary layer and the infrared-reflective layer. In these embodiments,the coating 40 can optionally include inner 30 and outer 120 coats eachcomprising at least one transparent dielectric film.

[0031] In embodiments where the low solar reflectance coating 40 iscarried on the #2 surface of the IG unit 8, the high absorption primarylayer 80 is positioned closer to the pane 10 than theinfrared-reflective layer 150. In some embodiments of this nature, thelow solar reflectance coating 40 comprises, in sequence from thesubstrate 10 outwardly (i.e., not necessarily in a contiguous sequence):an inner coat 30 comprising at least one transparent dielectric film(preferably having a thickness of between about 108 Å and about 156 Å,more preferably between about 115 Å and about 150 Å, and perhapsoptimally between about 128 Å and about 136 Å); a high absorptionprimary layer 80 (e.g., comprising titanium, niobium, titanium nitride,or another highly absorptive material, preferably having a thickness ofat least about 100 Å, more preferably between about 104 Å and about 151Å, and perhaps optimally between about 110 Å and about 144 Å); a middlecoat 90 comprising at least one transparent dielectric film (preferablyhaving a thickness of between about 300 Å and about 435 Å, morepreferably between about 317 Å and about 416 Å, and perhaps optimallybetween about 353 Å and about 378 Å); an infrared-reflective layer 150(e.g., formed of silver or another electrically-conductive material,preferably having a thickness of at least about 175 Å, more preferablybetween about 182 Å and about 274 Å, and perhaps optimally between about193 Å and about 262 Å); a high absorption blocker layer 180 (e.g.,comprising titanium, niobium, or another highly absorptive material,preferably having a thickness of at least about 45 Å, more preferablybetween about 46 Å and about 78 Å, and perhaps optimally between about48 Å and about 75 Å); and an outer coat 120 comprising at least onetransparent dielectric film (preferably having a thickness of betweenabout 205 Å and about 291 Å, more preferably between about 217 Å andabout 278 Å, and perhaps optimally between about 242 Å and about 253 Å).

[0032] The present low solar reflectance, low-emissivity coating 40 hasa number of beneficial properties. The ensuing discussion reportsseveral of these properties. In some cases, these properties arereported in the context of a single pane bearing the present coating onone surface. In other cases, these properties are reported in thecontext of an IG unit having the present coating 40 on its #2 surface.In such cases, the reported properties have been determined for an IGunit wherein both panes are 3mm soda-lime float glass, and wherein theIG unit has a ½ inch between-pane space filled with an insulative gasmix of 90% argon and 10% air. Of course, these specifics are by no meanslimiting to the invention. Absent an express statement to the contrary,the present discussion reports determinations made using Window 4.1under standard ASHRAE conditions.

[0033] An IG unit bearing a conventional double silver low-emissivitycoating would typically have an exterior (i.e., off the glass side ofthe outboard pane) solar reflectance R_(s) of at least about 30%-35%.Given the solar reflection problems discussed above, it would bedesirable to provide a low-emissivity coating that offers lower solarreflection. The present IG unit 8 achieves an exterior solar reflectanceR_(s) of less than about 30%. In fact, the present IG unit 8 achieves anexterior solar reflectance R_(s) of less than about 20%. While theprecise level of solar reflection can be selected and varied inaccordance with the teachings of this disclosure, certain preferredembodiments (e.g., where the coating 40 is one of the three uniquelypreferred film stacks detailed below) provide an IG unit 8 having anexterior solar reflectance R_(s) of about 16%.

[0034] The term “solar reflectance” is well known in the present art.This term is used herein in accordance with its well-known meaning torefer to the percentage of incident solar radiation SR that is reflectedoff the glass side of a monolithic pane (which bears the coating 40 onthe opposite film side) or off the exterior of the present IG unit 8.Skilled artisans will appreciate that the solar reflectance off theglass side of the monolithic pane includes not only solar radiationreflected at the surface 12, but also solar radiation reflected at thesurface 14. Likewise, the solar reflectance off the exterior side of theIG unit 8 (measured from the exterior 77 of the unit 8) includes notonly solar radiation reflected at the surface 12, but also solarradiation reflected at surfaces 14, 14′, and 12′. The reported solarreflectance is measured off a central portion of the glass side of themonolithic pane or off a central portion of the glass side of theoutboard pane 10 of the present IG unit 8, is indicated as R_(s) where sstands for solar. The solar reflectance can be determined as specifiedin “Standard Test Methods for Solar Energy Transmittance and Reflectance(Terrestrial) of Sheet Materials, ASTM”, the entire contents of whichare incorporated herein by reference.

[0035]FIG. 6 is a graph showing the glass-side reflectance of amonolithic pane bearing the present low solar reflectance coating(denoted by the solid line) relative to the glass-side reflectance of amonolithic pane bearing a double silver low-emissivity coating (denotedby the dashed line). The reflectance is reported in FIG. 6 forwavelengths between about 300 nm and about 2,500 nm. This wavelengthrange is of interest because the solar radiation that reaches the earthis primarily in this range. In FIG. 6, it can be appreciated that thetotal solar reflection of the present coating 40 is far less than thatof the double-silver coating. Thus, the present coating 40 offersexceptionally low solar reflection.

[0036] In addition to low solar reflectance, the present coating 40 hasexceptional shading ability. For example, the solar heat gaincoefficient (SHGC) of the present IG unit 8 is particularly low. As iswell known in the present art, the solar heat gain coefficient of awindow is the fraction of incident solar radiation that is admittedthrough the window. The term “solar heat gain coefficient” is usedherein in accordance with its well known meaning. Reference is made toNFRC 200-93 (1993), the entire teachings of which are incorporatedherein by reference.

[0037] As noted above, there are many applications where low solar heatgain windows are of particular benefit. In warm climates, for example,it is desirable to have low solar heat gain windows. Further, anywindows that are exposed to a lot of undesirable sun should have a lowsolar heat gain coefficient. For applications like these, the solar heatgain coefficient plays a vital role in maintaining a comfortableenvironment within a building. Thus, it is beneficial to provide windowsof this nature with coatings that establish a low solar heat gaincoefficient. For example, a solar heat gain coefficient of about 0.4 orless is commonly recommended for buildings in the southern United Statesand other warm climates.

[0038] The exceptional shading ability of the low solar reflectancecoating 40 is particularly beneficial for warm climate applications. Forexample, the present IG unit 8 has a solar heat gain coefficient of lessthan about 0.4. In fact, the IG unit 8 has a solar heat gain coefficientof less than about 0.3, and preferably less than about 0.2. While theprecise level of shading ability can be selected and varied inaccordance with the teachings of this disclosure, certain preferredembodiments (e.g., where the coating 40 is one of the three uniquelypreferred film stacks detailed below) provide an IG unit 8 having asolar heat gain coefficient of about 0.16. Thus, the low solarreflectance coating 40 is particularly beneficial when high shadingability is desired.

[0039] A limitation of some high shading ability coatings is that theyreflect more visible light than is desired. As noted above, a tradeoffis sometimes made in high shading ability coatings whereby the filmsselected to achieve a low SHGC have the effect of restricting thevisible reflectance to a level that is higher than ideal. As aconsequence, windows bearing these coatings may have a somewhatmirror-like appearance.

[0040] To the contrary, the present coating 40 has sufficiently lowvisible reflectance to obviate this mirror-like appearance problem. Forexample, the exterior visible reflectance R_(v) of the present IG unit 8is less than about 20%. In fact, the IG unit 8 achieves an exteriorvisible reflectance R_(v) of less than about 18%. While the preciselevel of visible reflectance can be selected and varied in accordancewith the present teachings, certain preferred embodiments (e.g., wherethe coating 40 is one of the three uniquely preferred film stacksdetailed below) achieve an IG unit 8 having an exterior visiblereflectance R_(v) of about 11%. In contrast, the exterior visiblereflectance of an IG unit having panes of clear uncoated glass wouldtypically be about 15%. The extraordinarily low visible reflectance ofthe coating 40 is exceptional considering the great thickness of theinfrared-reflective layer. This evidences the surprising results thatare achieved by the particular combination of films used in the presentcoating 40.

[0041] The term “visible reflectance” is well known in the present art.This term is used herein in accordance with its well-known meaning torefer to the percentage of all incident visible radiation that isreflected off the glass side of a monolithic pane (which bears thecoating 40 on the opposite film side) or off the exterior of the presentIG unit 8. Skilled artisans will appreciate that the visible reflectanceoff the glass side of a monolithic pane includes not only visibleradiation reflected at the surface 12, but also visible radiationreflected at the surface 14. Likewise, the visible reflectance off theexterior side of the IG unit 8 (measured from the exterior 77 of theunit 8) includes not only visible radiation reflected at the surface 12,but also visible radiation reflected at surfaces 14, 14′, and 12′. Thereported visible reflectance is measured off a central portion of theglass side of the monolithic pane or off a central portion of the glassside of the outboard pane 10 of the present IG unit 8, and is indicatedas R_(v) where v stands for visible. Visible reflectance can bedetermined as specified in the above-noted “Standard Test Methods forSolar Energy Transmittance and Reflectance (Terrestrial) of SheetMaterials, ASTM”.

[0042] Reference is made once again to FIG. 6, wherein there isillustrated the glass-side reflectance of a monolithic pane bearing thepresent coating 40 on one surface. Visible radiation comprises thewavelength range from about 380 nm to about 780 nm. As shown in FIG. 6,the glass-side reflectance of a pane bearing the present coating 40 isabout 10% over a major portion (in fact, over substantially all) of thevisible wavelength range. Further, the reflectance is well below 20%(and, in fact, does not exceed about 15%) over the entire visible range.Thus, it can be appreciated that the present coating 40 offersexceptionally low visible reflectance.

[0043]FIG. 9 shows transmission properties of a monolithic pane bearingthe present coating 40 on one surface. As can be appreciated, thetransmittance of the pane is highest across the visible range ofwavelengths. Peak transmittance occurs between the wavelengths of about400 nm and 450 nm and is about 18%-19%. Transmittance decreases atwavelengths outside the visible range. As will be appreciated by skilledartisans, these transmission properties are highly desirable for avariety of applications, such as high shading applications.

[0044] In addition to these beneficial properties, the present coating40 achieves color properties that are particularly pleasing. Thefollowing discussion of transmitted and reflected color is reportedusing the well known color coordinates of “a” and “b”. In particular,these color coordinates are indicated herein using the subscript h(i.e., a_(h) and b_(h)) to represent conventional use of the well knownHunter Lab Color System (Hunter methods/units, III. D65, 10 degreeobserver). The present color properties can be determined as specifiedin ASTM D-2244-93, “Standard Test Method For Calculation Of ColorDifferences From Instrumentally Measured Color Coordinates”, Sep. 15,1993, as augmented by ASTM E-308-85 Annual Book of ASTM Standards, Vol.06.01 “Standard Method For Computing The Colors Of Objects By Using TheCIE System”, the entire contents of each of which are incorporatedherein by reference.

[0045] The present IG unit 8 exhibits a transmitted color that isparticularly pleasing. As noted above, it is commonly desirable forwindows to exhibit hues of blue or blue-green. The transmitted hue ofthe present IG unit 8 falls entirely within the blue-green range. Inparticular, the IG unit 8 exhibits a transmitted color characterized byan a_(h) color coordinate of between about −1.75 and about −4.5 and ab_(h) color coordinate of between about −2 and about −5. In certainpreferred embodiments (e.g., where the low solar reflectance coating 40is one of the three uniquely preferred film stacks detailed below), theIG unit 8 exhibits a transmitted color characterized by an a_(h) colorcoordinate of between about −2.1 and about −4.2 and a b_(h) colorcoordinate of between about −2.5 and about −4.5. This can be appreciatedwith reference to FIG. 7, wherein the transmitted color of such an IGunit 8 is represented by the color box defined by the dashed lines. Inthis figure, it can be appreciated that the transmitted a_(h) and b_(h)color values are both negative, such that the transmitted hue is in theblue-green range. Further, the magnitude of the negative a_(h) and b_(h)values is very low, indicating very low chroma/very good colorneutrality. Thus, when the present coating 40 is provided on an IG unit,the resulting unit 8 exhibits a particularly pleasing transmitted color.Accordingly, the present coating 40 is especially desirable forapplications where transmitted color is of particular interest, such asin sunrooms, solariums, greenhouses, and the like.

[0046] The present IG unit 8 also exhibits a very pleasing color inreflection. The reflected color reported herein is measured from theexterior 77′ of the IG unit 8. The present IG unit 8 is nearly colorlessin reflection. In particular, the IG unit 8 exhibits a reflected colorcharacterized by an a_(h) color coordinate of between about 1.4 andabout −1.6 and a b_(h) color coordinate of between about 0.5 and about−2.5. In certain preferred embodiments (e.g., where the coating 40 isone of the three uniquely preferred film stacks detailed below), the IGunit 8 exhibits a reflected color characterized by an a_(h) colorcoordinate of between about 0.9 and about −1.2 and a b_(h) colorcoordinate of between about 0.0 and about −2. This is shown in FIG. 8,wherein the reflected color of such an IG unit 8 is represented by thecolor box defined by the dashed lines. In this figure, it can beappreciated that the chroma of the reflected color is exceptionally low,indicating that the coating 40 is nearly colorless.

[0047] In addition to the beneficial properties discussed above, thepresent IG unit 8 has exceptional thermal insulating properties. Asnoted above, the low solar reflectance coating 40 includes at least oneinfrared-reflective film 150. This film 150 is highly reflective ofinfrared radiation (i.e., radiant heat). Since the infrared-reflectivefilm 150 is typically formed of silver or another electricallyconductive material, this film 150 contributes low emissivity to the lowsolar reflectance coating 40. For example, the emissivity of the presentcoating 40 is less than about 0.07. In fact, the emissivity of thiscoating 40 is less than about 0.05. While the precise level ofemissivity can be selected and varied in accordance with the presentteachings, a number of preferred coating embodiments (e.g., the threeuniquely preferred film stacks detailed below) provide an emissivity ofabout 0.044. In contrast, an uncoated pane of clear glass wouldtypically have an emissivity of about 0.84. Thus, the present coating 40achieves exceptionally low emissivity, and yet has excellent colorproperties and exceptionally low visible reflectance. This surprisingcombination of properties further evidences the extraordinary resultsthat are achieved by the particular combination of films used in thepresent coating 40.

[0048] The term “emissivity” is well known in the present art. This termis used herein in accordance with its well-known meaning to refer to theratio of radiation emitted by a surface to the radiation emitted by ablackbody at the same temperature. The present emissivity values can bedetermined as specified in “Standard Test Method For Emittance OfSpecular Surfaces Using Spectrometric Measurements” NFRC 301-93, theentire contents of which are incorporated herein by reference.

[0049] The “U Value” of the present IG unit 8 is also exceptionally low.As is well known, the U Value of an IG unit is a measure of the thermalinsulating ability of the unit. The smaller the U value the better thethermal insulating ability of the unit. The U Value of the present IGunit 8 is less than about 0.4. In fact, the IG unit 8 has U Value ofless than about 0.3. While the precise level of U Value can be selectedand varied in accordance with the present teachings, certain preferredembodiments (e.g., where the coating 40 is one of the three uniquelypreferred film stacks detailed below) provide an IG unit 8 wherein the UValue is about 0.25. In comparison, the U Value of an IG unit havingpanes of uncoated glass would typically be about 0.46. Thus, the presentcoating 40 facilitates exceptionally low U Value.

[0050] The term U Value is well known in the present art. It is usedherein in accordance with its well-known meaning to express the amountof heat that passes through one unit of area in one unit of time foreach unit of temperature difference between a hot side of the IG unit 8and a cold side of the IG unit 8. The U Value can be determined inaccordance with the standard specified for U_(winter) in NFRC 100-91(1991), the entire contents of which are incorporated herein byreference.

[0051]FIG. 2 depicts a preferred low solar reflectance coating 40 of theinvention. As can be appreciated, the illustrated coating 40 generallyincludes the following sequence of films, moving outwardly (i.e., awayfrom the substrate): a transparent dielectric inner coat 30; a highabsorption primary layer 80; a transparent dielectric middle coat 90; aninfrared-reflective layer 150; a high absorption blocker layer 180; anda transparent dielectric outer coat 120. The present disclosure teachesparticular combinations of thicknesses and materials for these films,which combinations achieve the exceptional properties described above.

[0052] As noted above, the present coating 40 includes aninfrared-reflective film 150. This infrared-reflective film 150 ispreferably formed of an electrically-conductive material (e.g., metal),such as silver, gold, copper, or the like. Alloys or mixtures of thesemetals can also be used. In most cases, it will be preferable to employa silver or silver-containing film (e.g., comprising a major weightpercentage of silver). The term “silver-containing” is used herein torefer to any film that includes at least some silver. For example, onemay provide an infrared-reflective film in the form of silver combinedwith a small amount of gold (e.g., about 5% gold or less).

[0053] The infrared-reflective film 150 is highly reflective of infraredradiation. As a result, this film 150 substantially reduces thetransmission of radiant heat through the coating 40. Further, theelectrically-conductive material of this film 150 has low sheetresistance, and hence low emissivity. Thus, the infrared-reflective film150 contributes low emissivity to the coating 40. As noted above, theseproperties are desirable for coatings on windows and other glazings(e.g., doors, skylights, etc.). For example, during a cold winter it isdesirable to minimize the heat that escapes from a warm room through awindow to a cold outdoor environment. Likewise, during a warm summer itis desirable to minimize the heat that enters a cool room through awindow from a hot outdoor environment. Thus, the infrared-reflectivefilm 150 is advantageous in that it helps reduce the amount of heat thatpasses through the coating 40.

[0054] The infrared-reflective film 150 is preferably provided atparticular thicknesses. The thickness of this film 150 is desirably atleast about 175 Å, preferably between about 182 Å and about 274 Å, morepreferably between about 193 Å and about 262 Å, and perhaps optimallybetween about 215 Å and about 238 Å. Forming the infrared-reflectivelayer 150, especially of silver or a silver-containing film, at thesethicknesses is particularly preferred.

[0055] The low solar reflectance coating 40 preferably includes a highabsorption primary layer 80. The high absorption primary layer 80 ispreferably formed of particular materials. For example, this primarylayer 80 preferably comprises titanium, niobium, or another materialthat is highly absorptive of solar radiation (e.g., a highly absorptivedielectric material, such as titanium nitride). The high absorptionprimary layer 80 absorbs a substantial portion of incident solarradiation. In certain preferred embodiments, the primary layer 80comprises metallic titanium, metallic niobium, or another metallicmaterial that is highly absorptive of solar radiation. Thus, the layer80 may consist, or consist essentially, of a highly absorptive metallicmaterial. In some cases, all but a portion of the high absorptionprimary layer 80 is metallic. In such cases, the outer portion (i.e.,the portion furthest from the substrate) of this layer 80 may beoxidized, nitrided, or otherwise reacted to some extent. This tends tooccur when the high absorption primary layer 80 is deposited as metallicfilm, and the deposition of a subsequent film is performed in a reactive(e.g., oxidizing and/or nitriding) atmosphere. In such cases, the outerface of the primary layer 80 is exposed to the reactive atmosphereduring an initial period of the subsequent film deposition, such thatthe outer portion 80′ of the primary layer 80 is oxidized, nitrided,and/or otherwise reacted. In these embodiments, it is desirable if nomore than a minor portion (e.g., less than 50% of the thickness) of theprimary layer 80 is a reaction product (e.g., an oxide, nitride, and/oroxynitrides), and a major portion (e.g., 50% or more of the thickness)thereof is metallic. Thus, it can be appreciated that certainembodiments involve a high absorption primary layer 80 that consists, orconsists essentially, of a highly absorptive metallic material andreaction products of such metallic material.

[0056] The high absorption primary layer 80 is preferably provided atparticular thicknesses. The thickness of the high absorption primarylayer 80 is desirably at least about 100 Å, preferably between about 104Å and about 151 Å, more preferable between about 110 Å and about 144 Å,and perhaps optimally between about 123 Å and about 131 Å. Forming thehigh absorption primary layer 80 at these thicknesses is particularlypreferred, especially when this layer 80 is formed of particularmaterials, as will now be described.

[0057] In certain particularly preferred embodiments, the highabsorption primary layer 80 comprises titanium. In one embodiment, thislayer 80 is a titanium-containing film having a thickness within atleast one of the ranges described in the preceding paragraph. The term“titanium-containing” is used herein to refer to any film that containsat least some titanium. Thus, absent an express statement to thecontrary, materials other than titanium may be present in such a film.In some cases, the high absorption primary layer 80 is atitanium-containing film that consists, or consists essentially, oftitanium. In other cases, this layer 80 is a titanium-containing filmhaving an outer portion 80′ that is a reaction product of titanium(e.g., titanium oxide, titanium nitride, and/or titanium oxynitride). Insuch cases, it will generally be preferred if a major inner portion(i.e., 50% or more) of the titanium-containing film is metallictitanium, while a minor outer portion (i.e., less than 50%) is atitanium reaction product. For example, the high absorption primarylayer 80 can be a titanium-containing film wherein metallic titaniumaccounts for at least about 62 Å, more preferably at least about 75 Å,and perhaps optimally at least about 80 Å of this layer 80 (e.g., whereat least the innermost 62 Å, 75 Å, or 80 Å is metallic titanium). Incertain embodiments, the high absorption primary layer is deposited as ametallic titanium film.

[0058] In certain embodiments, the high absorption primary layer 80comprises niobium. In one embodiment, this layer 80 is aniobium-containing film having a thickness within at least one of thedescribed ranges. The term “niobium-containing” is used herein to referto any film that contains at least some niobium. Absent an expressstatement to the contrary, materials other than niobium may be presentin such a film. In some cases, the high absorption primary layer 80 is aniobium-containing film that consists, or consists essentially, ofniobium. In other cases, this layer 80 is a niobium-containing filmhaving an outer portion 80′ that is a reaction product of niobium (e.g.,niobium oxide, niobium nitride, and/or niobium oxynitride). In suchcases, it will generally be preferred if a major inner portion of theniobium-containing film is metallic niobium, while a minor outer portionis a niobium reaction product. For example, the high absorption primarylayer 80 can be a niobium-containing film wherein metallic niobiumaccounts for at least about 62 Å, more preferably at least about 75 Å,and perhaps optimally at least about 80 Å of this layer 80 (e.g., whereat least the innermost 62 Å, 75 Å, or 80 Å is metallic niobium). Incertain embodiments, the high absorption primary layer is deposited as ametallic niobium film.

[0059] In certain embodiments, the high absorption primary layer 80comprises both niobium and titanium. In one embodiment, this layer 80 isa niobium-titanium-containing film having a thickness within at leastone of the described ranges. The term “niobium-titanium-containing” isused herein to refer to any film that contains at least some niobium andat least some titanium. Absent an express statement to the contrary,materials other than niobium and titanium may be present in such a film.Useful niobium-titanium films and methods for their deposition aredescribed in U.S. patent application Ser. No. 10/123,032, filed on Apr.11, 2002 and entitled “Thin Film Coating Having Niobium-Titanium Layer”,the entire contents of which are incorporated herein by reference. Insome cases, the high absorption primary layer 80 is aniobium-titanium-containing film that consists, or consists essentially,of niobium and titanium. In other cases, this layer 80 is aniobium-titanium-containing film having an outer portion 80′ that is areaction product of a niobium-titanium material. In such cases, it willgenerally be preferred if a major inner portion of thisniobium-titanium-containing film is metallic niobium-titanium (e.g., analloy of niobium and titanium), while a minor outer portion is aniobium-titanium reaction product. For example, the high absorptionprimary layer 80 can be a niobium-titanium-containing film whereinmetallic niobium-titanium accounts for at least about 62 Å, morepreferably at least about 75 Å, and perhaps optimally at least about 80Å of this layer 80 (e.g., where at least the innermost 62 Å, 75 Å or 80Å is metallic niobium-titanium). In certain embodiments, the highabsorption primary layer is deposited as a metallic niobium-titaniumfilm.

[0060] In certain embodiments, the high absorption primary layer 80comprises a dielectric film that is highly absorptive of solarradiation. In one such embodiment, the high absorption primary layer 80comprises (e.g., consists essentially of) titanium nitride. Of course,skilled artisans may wish to select other known high absorptiondielectric films.

[0061] With continued reference to the preferred embodiment of FIG. 2,it can be appreciated that the coating 40 preferably includes a highabsorption blocker layer 180. This blocker layer 180 is preferablydeposited directly over the infrared-reflective film 150. The preferredhigh absorption blocker layer 180 serves a number of purposes. Forexample, this layer 180 protects the underlying infrared-reflective film150 during the deposition of subsequent films. This blocker layer 180preferably comprises a metal or metal alloy that reacts readily withoxygen, nitrogen, or other reactive gas used in depositing subsequentfilms. This allows the blocker layer 180 to capture reactive gas thatwould otherwise reach and react with the infrared-reflective film 150.In addition, the high absorption blocker layer 180 provides theinfrared-reflective film 150 with exceptional protection againstchemical corrosion. This is believed to be a result of the relativelygreat thickness of the high absorption blocker layer 180, as compared toconventional blocker layers. The protective properties of the highabsorption blocker layer 180 are credited in part for the outstandingchemical durability that has been observed in the present coating 40.Further, the high absorption blocker layer 180 affords exceptionalcontrol over the transmitted color of the present coating 40. Asdescribed above, the transmitted color of the present coating 40 isexceptionally color neutral, and this is attributed in part to theparticular composition and thickness of the high absorption blockerlayer 180.

[0062] The high absorption blocker layer 180 is preferably provided atparticular thicknesses. The thickness of this layer 180 is desirably atleast about 45 Å, preferably between about 46 Å and about 78 Å, morepreferably between about 48 Å and about 75 Å, and perhaps optimallybetween about 54 Å and about 68 Å. Forming the high absorption blockerlayer 180 at these thicknesses is particularly preferred, especiallywhen this layer 180 is formed of particular materials, as will now bedescribed.

[0063] In a number of particularly preferred embodiments, the highabsorption blocker layer 180 comprises titanium. In certain embodiments,this layer 180 is a titanium-containing film having a thickness withinat least one of the ranges described in the preceding paragraph. Thehigh absorption blocker layer 180 can be a titanium-containing film thatconsists, or consists essentially, of titanium. Alternatively, thislayer 180 can be a titanium-containing film having an outer portion thatis a reaction product of titanium (e.g., titanium oxide, titaniumnitride, and/or titanium oxynitride). In such cases, it will generallybe preferred if a major inner portion of the titanium-containing film ismetallic titanium, while a minor outer portion is a titanium reactionproduct. Thus, the high absorption blocker layer 180 can be atitanium-containing film wherein metallic titanium accounts for at leastabout 23 Å, more preferably at least about 25 Å, and perhaps optimallyat least about 27 Å of this layer 180 (e.g., where at least theinnermost 23 Å, 25 Å, or 27 Å is metallic titanium).

[0064] In certain embodiments, the high absorption blocker layer 180comprises niobium. In some embodiments of this nature, the highabsorption blocker layer 180 is a niobium-containing film having athickness within at least one of the described ranges. The highabsorption blocker layer 180 can be a niobium-containing film thatconsists, or consists essentially, of niobium. Alternatively, this layer180 can be a niobium-containing film having an outer portion that is aniobium reaction product. In such cases, it will generally be preferredif a major inner portion of the niobium-containing film is metallicniobium, while a minor outer portion is a niobium reaction product. Forexample, the high absorption blocker layer 180 can be aniobium-containing film wherein metallic niobium accounts for at leastabout 23 Å, more preferably at least about 25 Å, and perhaps optimallyat least about 27 Å of this layer 180 (e.g., where at least theinnermost 23 Å, 25 Å, or 27 Å is metallic niobium).

[0065] In certain embodiments, the high absorption blocker layer 180comprises both niobium and titanium. Useful niobium-titanium blockerlayers are described in the above-noted '032 patent application. In someembodiments of this nature, the high absorption blocker layer 180 is aniobium-titanium-containing film having a thickness within at least oneof the noted ranges. The high absorption blocker layer 180 can be aniobium-titanium-containing film that consists, or consists essentially,of a niobium-titanium material (e.g., alloys of niobium and titanium).Alternatively, the high absorption blocker layer 180 can be aniobium-titanium-containing film having an outer portion that is areaction product of niobium-titanium. In such cases, it will generallybe preferred if a major inner portion of the niobium-titanium-containingfilm is metallic niobium-titanium, while a minor outer portion ispresent in the form of a niobium-titanium reaction product. For example,the high absorption blocker layer 180 can be aniobium-titanium-containing film wherein metallic niobium-titaniumaccounts for at least about 23 Å, more preferably at least about 25 Å,and perhaps optimally at least about 27 Å of this layer 180 (e.g., whereat least the innermost 23 Å, 25 Å, or 27 Å is metallicniobium-titanium).

[0066] The low solar reflectance coating 40 is preferably provided witha transparent dielectric inner coat 30, a transparent dielectric middlecoat 90, and a transparent dielectric outer coat 120. The transparentdielectric films 30, 90, 120 are preferred to establish theexceptionally well-balanced properties of the present coating 40. Forexample, these preferred films reduce the visible reflectance of thecoating 40, control the color of the coating 40, and impart chemicaldurability in the coating 40. The preferred inner coat 30 is positionedbetween the substrate 10 and the high absorption primary layer 80, whilethe preferred outer coat 120 is positioned further from the substrate 10than the infrared-reflective film 150. In some cases, the preferredinner coat 30 is contiguous to the substrate 10. However, the inventionalso provides embodiments wherein a transparent base layer 20 (notshown) is positioned between the preferred inner coat 30 and thesubstrate 10. Useful transparent base layers 20 are described in U.S.patent application Ser. No. 10/087,662, the entire contents of which areincorporated herein by reference. In certain embodiments, the preferredouter coat 120 forms the outermost film region of the present coating40. Alternatively, a variety of overcoats can be positioned further fromthe substrate than the preferred outer coat, if so desired.

[0067] The preferred inner 30 and outer 120 coats each comprise at leastone transparent dielectric film. The term “transparent dielectric” isused herein to refer to any non-metallic (i.e., neither a pure metal nora metal alloy) compound that includes any one or more metals and issubstantially transparent when deposited as a thin film. For example,included in this definition would be any metal oxide, metal nitride,metal carbide, metal sulfide, metal boride, and any combination thereof(e.g., an oxynitride). Further, the term “metal” should be understood toinclude all metals and semi-metals (i.e., metalloids). In particular,useful metal oxides include oxides of zinc, tin, indium, bismuth,titanium, hafnium, zirconium, and alloys and mixtures thereof. Whilemetal oxides are advantageous due to their ease and low cost ofapplication, known metal nitrides (e.g., silicon nitride, titaniumnitride, etc.) can also be used advantageously. Skilled artisans will befamiliar with other useful transparent dielectric materials.

[0068] The preferred inner coat 30 is preferably provided at particularthicknesses. For example, the physical thickness of the inner coat 30 ispreferably between about 108 Åand about 156 Å, more preferably betweenabout 115 Å and about 150 Å, and perhaps optimally between about 128 Åand about 136 Å. In a first embodiment, the inner coat 30 is a singlezinc oxide film. In a second embodiment, the inner coat 30 is a singletitanium oxide film (e.g., titanium dioxide and/or substoichiometricTiO_(x), where x is less than 2). In a third embodiment, the inner coat30 is a single silicon nitride film. In a fourth embodiment, the innercoat 30 is a single tin oxide film. In each of these four embodiments,the thickness of the inner coat 30 is preferably within at least one ofthe ranges described in this paragraph.

[0069] In certain alternate embodiments (not shown), the inner coat 30comprises at least two films. The preferred inner coat 30 can be formedof essentially any desired number of films. However, the total opticalthickness of the inner coat 30 (whether it consists of one or multiplefilms) is preferably between about 216 Å and about 312 Å, morepreferably between about 230 Å and about 300 Å, and perhaps optimallybetween about 256 Å and about 272 Å. In certain embodiments, each filmof the inner coat 30 is a transparent dielectric film having arefractive index of between about 1.7 and about 2.4, and perhapsoptimally about 2.0.

[0070] The exceptional properties of the present coating 40 are due inpart to the thinness of the preferred inner coat 30. Excellentantireflection and color is achieved by providing the preferred innercoat 30 at an optical thickness of less than about 312 Å, morepreferably less than about 300 Å, and perhaps optimally less than about272 Å, while desirably having an optical thickness of at least about 216Å.

[0071] The preferred outer coat 120 is also preferably provided atparticular thicknesses. For example, the physical thickness of the outercoat 120 is preferably between about 205 Å and about 291 Å, morepreferably between about 217 Å and about 278 Å, and perhaps optimallybetween about 242 Å and about 253 Å. In a first embodiment, the outercoat 120 is a single zinc oxide film. In a second embodiment, the outercoat 120 is a single titanium oxide film. In a third embodiment, theouter coat 120 is a single silicon nitride film. In a fourth embodiment,the outer coat 120 is a single tin oxide film. In each of these fourembodiments, the thickness of the outer coat 120 preferably is within atleast one of the ranges described in this paragraph.

[0072] In a number of preferred embodiments (not shown), the outer coat120 comprises at least two films. As with the inner coat 30, thepreferred outer coat 120 can be formed of essentially any desired numberof films. However, the total optical thickness of the outer coat 120(whether it consists of one or multiple films) is preferably betweenabout 410 Å and about 582 Å, more preferably between about 434 Å andabout 556 Å, and perhaps optimally between about 484 Å and about 506 Å.In certain embodiments, each film of the outer coat 120 is a transparentdielectric film having a refractive index of between about 1.7 and about2.4, and perhaps optimally about 2.0.

[0073] In certain preferred embodiments, the outer coat 120 comprisestwo outer films of different transparent dielectric materials. Thesefilms can be formed respectively of essentially any two transparentdielectric materials. In some cases, these films are contiguous to oneanother, although this is not required. In one embodiment, the outercoat 120 comprises a first layer of zinc oxide and a second layer ofsilicon nitride positioned over (e.g., directly over) the zinc oxidelayer. Alternatively, the first layer can be titanium oxide and thesecond layer can be silicon nitride. As still another alternative, thefirst layer can be tin oxide and the second layer can be siliconnitride. As yet another alternative, the first layer can be zinc oxideand the second layer can be titanium oxide or tin oxide. The respectivethicknesses of these outer films can be selected and varied as desired.Preferably, the combined optical thickness of these two films is withinat least one of the ranges described in the preceding paragraph.

[0074] In embodiments where the outer coat 120 comprises multiple films,the outermost of these films preferably comprises a chemically-durablematerial, such as silicon nitride. U.S. Pat. No. 5,834,103, the entirecontents of which are incorporated herein by reference, describessilicon nitride films that can be used advantageously as the outermostfilm in the present coating 40. In certain particularly preferredembodiments, the outermost film is silicon nitride deposited at athickness of between about 15 Å and about 46 Å, more preferably betweenabout 16 Å and about 44 Å, and perhaps optimally between about 18 Å andabout 40 Å.

[0075] A chemically-durable film of the nature (e.g., of the thicknessand composition) just described can be deposited advantageously over(i.e., further from the substrate than) an underlying, outer transparentdielectric film having a thickness of between about 177 Å and about 270Å, more preferably of between about 189 Å and about 259 Å, and perhapsoptimally between about 209 Å and about 235 Å. In certain embodiments,this underlying (e.g., directly underlying) transparent dielectric filmis formed of zinc oxide, titanium oxide, or tin oxide. In particular,the high sputtering rate of zinc oxide makes it a preferred material forthis underlying, outer transparent dielectric film.

[0076] The exceptional optical properties of the present coating 40 aredue in part to the thinness of the preferred outer coat 120. Excellentantireflection and color is achieved by providing the preferred outercoat 120 at an optical thickness of less than about 582 angstroms, morepreferably less than about 556 angstroms, and perhaps optimally lessthan about 506 angstroms, while desirably having an optical thickness ofat least about 410 angstroms.

[0077] The low solar reflectance coating 40 is preferably provided witha transparent dielectric middle coat 90 between the high absorptionprimary layer 80 and the infrared-reflective layer 150. The preferredmiddle coat 90 comprises at least one transparent dielectric film. Incertain preferred embodiments, the middle coat 90 is provided in theform of a single transparent dielectric film. This film can comprise anyof the transparent dielectric materials described above. In oneembodiment, the middle coat 90 is a single zinc oxide film.

[0078] The transparent dielectric middle coat 90 is preferably providedat particular thicknesses. For example, the physical thickness of themiddle coat 90 is preferably between about 300 Å and about 435 Å, morepreferably between about 317 Å and about 416 Å, and perhaps optimallybetween about 353 Å and about 378 Å. Forming the transparent dielectricmiddle coat 90 at these thicknesses is particular preferred. Thethicknesses noted herein are physical thicknesses, unless specificallyidentified as being optical thicknesses.

[0079] In alternate embodiments (not shown), the middle coat 90 isprovided in the form of a plurality of transparent dielectric films.Whether the middle coat 90 consists of one or multiple films, theoverall optical thickness of this coat 90 is preferably between about600 Å and about 872 Å, more preferably between about 636 Å and about 832Å, and perhaps optimally between about 706 Å and about 756 Å. In certainembodiments, each film in the middle coat 90 is a transparent dielectricfilm having a refractive index of between about 1.7 and about 2.4, andperhaps optimally about 2.0.

[0080] The exceptional optical properties of the present coating 40 aredue in part to the relative optical thicknesses of the preferred innercoat 30, the preferred middle coat 90, and the preferred outer coat 120.For example, in certain embodiments, there is provided a specific ratioof the optical thickness of the inner coat 30 relative to the opticalthickness of the middle coat 90. Additionally or alternatively, therecan be provided a specific ratio of the optical thickness of the outercoat 120 relative to the optical thickness of the middle coat 90.

[0081] In certain embodiments, the ratio of optical thickness of theinner coat 30 to the optical thickness of the middle coat 90 ispreferably between about 0.28 and about 0.47, more preferably betweenabout 0.34 and about 0.39, and perhaps optimally about 0.35-0.36.Further, in certain embodiments, the ratio of the optical thickness ofthe outer coat 120 to the optical thickness of the middle coat 90 ispreferably between about 0.52 and about 0.88, more preferably betweenabout 0.64 and about 0.72, and perhaps optimally about 0.67-0.69. Incertain preferred embodiments, the coating 40 has one of the foregoingratios of inner coat/middle coat as well as one of the foregoing ratiosof outer coat/middle coat.

[0082] Three uniquely preferred low solar reflectance film stack 40embodiments will now be detailed. Each of these film stacks ispreferably utilized as a second-surface coating. In particular, whereone of these film stacks is born on the #2 surface of an IG unit, theresulting unit 8 achieves all of the beneficial properties noted above.While the present disclosure focuses somewhat on IG unit embodiments, itis to be understood that the invention extends to any substrate (e.g., amonolithic pane or a flexible sheet) carrying the present low solarreflectance, low-emissivity coating 40.

[0083] A first uniquely preferred low solar reflectance, low-emissivityfilm stack has the following structure: (1) a zinc oxide layer depositeddirectly upon a glass sheet at a thickness of between about 110 Å andabout 150 Å, more preferably between about 117 Å and about 143 Å, andoptimally about 130 Å; (2) a titanium layer deposited directly upon thiszinc oxide layer at a thickness of between about 111 Å and about 151 Å,more preferably between about 118 Å and about 144 Å, and optimally about131 Å, wherein an outer portion of this titanium layer is oxidizedduring deposition of the overlying zinc oxide film in an oxidizingatmosphere; (3) a zinc oxide layer deposited directly upon this titaniumlayer at a thickness of between about 303 Å and about 411 Å, morepreferably between about 321 Å and about 393 Å, and optimally about 357Å; (4) a silver layer deposited directly upon this zinc oxide layer at athickness of between about 185 Å and about 251 Å, more preferablybetween about 196 Å and about 240 Å, and optimally about 218 Å; (5) atitanium layer deposited directly upon this silver layer at a thicknessof between about 46 Å and 62 Å, more preferably between about 49 Å and59 Å, and optimally about 54 Å, wherein an outer portion of thistitanium layer is oxidized during deposition of the overlying zinc oxidefilm in an oxidizing atmosphere; (6) a zinc oxide layer depositeddirectly upon this titanium layer at a thickness of between 181 Å andabout 245 Å, more preferably between about 191 Å and about 235 Å, andoptimally about 213 Å; and (7) a silicon nitride layer depositeddirectly upon this zinc oxide layer at a thickness of between about 34 Åand 46 Å, more preferably between about 36 Å and about 44 Å, andoptimally about 40 Å.

[0084] A second uniquely preferred low solar reflectance, low-emissivityfilm stack has the following structure: (1) a zinc oxide layer depositeddirectly upon a glass sheet at a thickness of between about 108 Å andabout 148 Å, more preferably between about 115 Å and about 141 Å, andoptimally about 128 Å; (2) a titanium layer deposited directly upon thiszinc oxide layer at a thickness of between about 109 Å and about 149 Å,more preferably between about 116 Å and about 142 Å, and optimally about129 Å, wherein an outer portion of this titanium layer is oxidizedduring deposition of the overlying zinc oxide film in an oxidizingatmosphere; (3) a zinc oxide layer deposited directly upon this titaniumlayer at a thickness of between about 300 Å and about 406 Å, morepreferably between about 318 Å and about 388 Å, and optimally about 353Å; (4) a silver layer deposited directly upon this zinc oxide layer at athickness of between about 183 Å and about 247 Å, more preferablybetween about 193 Å and about 237 Å, and optimally about 215 Å; (6) atitanium layer deposited directly upon this silver layer at a thicknessof between about 53 Å and about 71 Å, more preferably between about 56 Åand about 68 Å, and optimally about 62 Å, wherein an outer portion ofthis titanium layer is oxidized during deposition of the overlying zincoxide film in an oxidizing atmosphere; (7) a zinc oxide layer depositeddirectly upon this titanium layer at a thickness of between about 200 Åand about 270 Å, more preferably between about 211 Å and about 259 Å,and optimally about 235 Å; and (8) a silicon nitride layer depositeddirectly upon this zinc oxide layer at a thickness of between about 15 Åand 21 Å, more preferably between about 16 Å and about 20 Å, andoptimally about 18 Å.

[0085] A third uniquely preferred low solar reflectance, low-emissivityfilm stack has the following structure: (1) a zinc oxide layer depositeddirectly upon a glass sheet at a thickness of between about 116 Å andabout 156 Å, more preferably between about 122 Å and about 150 Å, andoptimally about 136 Å; (2) a titanium layer deposited directly upon thiszinc oxide layer at a thickness of between about 105 Å and about 141 Å,more preferably between about 111 Å and about 135 Å, and perhapsoptimally about 123 Å, wherein an outer portion of this titanium layeris oxidized during deposition of the overlying zinc oxide film in anoxidizing atmosphere; (3) a zinc oxide layer deposited directly uponthis titanium layer at a thickness of between about 321 Å and about 435Å, more preferably between about 340 Å and about 416 Å, and optimallyabout 378 Å; (4) a silver layer deposited directly upon this zinc oxidelayer at a thickness of between about 202 Å and about 274 Å, morepreferably between about 214 Å and about 262 Å, and optimally about 238Å; (5) a titanium layer deposited directly upon this silver layer at athickness of between about 58 Å and about 78 Å, more preferably betweenabout 61 Å and about 75 Å, and optimally about 68 Å, wherein an outerportion of this titanium layer is oxidized during deposition of theoverlying zinc oxide film in an oxidizing atmosphere; (6) a zinc oxidelayer deposited directly upon this titanium layer at a thickness ofbetween 177 Å and about 241 Å, more preferably between about 188 Å andabout 230 Å, and optimally about 209 Å; and (7) a silicon nitride layerdeposited directly upon this zinc oxide layer at a thickness of betweenabout 28 Å and 38 Å, more preferably between about 30 Å and about 36 Å,and optimally about 33 Å.

[0086] The present low solar reflectance coatings 40 can be applied by avariety of well known coating techniques. For example, these coatingscan be applied by sputter deposition (i.e., sputtering). Sputtering iswell known in the present art. FIG. 3 depicts an exemplary magnetronsputtering chamber 200. Magnetron sputtering chambers and relatedequipment are commercially available from a variety of sources (e.g.,Leybold and BOC Coating Technology). Useful magnetron sputteringtechniques and equipment are described in U.S. Pat. No. 4,166,018,issued to Chapin, the entire contents of which are incorporated hereinby reference.

[0087] In favored methods of the invention, the substrate 10 is coatedin a multiple-chamber sputtering line. Sputtering lines are well knownin the present art. A typical sputtering line includes a series ofsputtering chambers that are aligned and connected such that asheet-like substrate 10 can be passed from one chamber to the next byconveying the substrate 10 horizontally over spaced-apart transportrollers 210 in each of the chambers. Thus, the rollers 210 form acontinuous path of substrate 10 travel through the sputtering line. Thesubstrate 10 is typically conveyed at speeds of between about 100-500inches per minute.

[0088] In one particular deposition method, the substrate 10 ispositioned at the inlet of the sputtering line and conveyed into a firstcoat zone. The first coat zone is provided with three cathodes adaptedto deposit the transparent dielectric inner coat 30. All three of thesecathodes comprise zinc sputtering targets. The zinc targets 240 in thefirst coat zone are sputtered in an oxidizing atmosphere to deposit azinc oxide inner coat 30. This oxidizing atmosphere may consistessentially of oxygen (e.g., about 100% O₂). Alternatively, thisatmosphere may comprise Ar/O₂ (e.g., at about 3.5 mbar). A power ofabout 37-39 kW is applied to each of the zinc targets, while thesubstrate 10 is conveyed beneath all three of these targets at a rate ofabout 475 inches per minute, such that a zinc oxide inner coat 30 isapplied at a thickness of about 128Å.

[0089] The substrate 10 is then conveyed into a second coat zone wherethe high absorption primary layer 80 is applied directly over the innercoat 30. This second coat zone preferably contains an inert atmosphere(e.g., argon at about 4 mbar). One of the sputtering bays in this coatzone has a titanium target. A power of about 68-69 kW is applied to thistitanium target, while the substrate is conveyed beneath this target ata rate of about 475 inches per minute, to deposit a titanium highabsorption primary layer 80 at a thickness of about 129 Å. The substrate10 is then conveyed through three subsequent active coat zones todeposit the transparent dielectric middle coat 90, as will now bedescribed.

[0090] The thus coated substrate is conveyed through a third coat zonehaving three sputtering bays each with a zinc target and then through afourth coat zone also having three sputtering bays each with a zinctarget. All six of these zinc targets are sputtered in an oxidizingatmosphere (as described above) to deposit the innermost portion of themiddle coat 90. The substrate 10 is conveyed beneath these six targetsat a rate of about 475 inches per minute, while a power of about 42-47kW is applied to each target.

[0091] The substrate 10 is then conveyed through a subsequent coat zonecontaining an oxidizing atmosphere. Two of the sputtering bays in thiszone are active and have zinc targets. The substrate is conveyed beneaththese targets at a rate of 475 inches per minute, while a power of about8-9 kW is applied to the first target and a power of about 46 kW isapplied to the second target. When the substrate 10 is conveyed beneaththese two zinc targets and the previous six zinc targets, a total ofabout 353 Å of zinc oxide is deposited directly on the titanium highabsorption primary layer 80. During deposition of this zinc oxide, theoutermost portion of the underlying titanium layer 80 is oxidized, asdescribed above.

[0092] The substrate 10 is then conveyed into a further coat zonewherein the infrared-reflective film 150 and the high absorption blockerlayer 180 are deposited. This coat zone preferably contains an inertatmosphere (described above). The first two sputtering bays of this coatzone each have a silver target. A power of about 13-14 kW is applied tothe first silver target and a power of about 7-8 kW is applied to thesecond silver target. The substrate 10 is conveyed beneath these twotargets at about 475 inches per minute, such that a silverinfrared-reflective layer 150 is deposited at a thickness of about 215Å. The third sputtering bay of this coat zone has a titanium target. Apower of about 33 kW is applied to this titanium target, while thesubstrate 10 is conveyed beneath this target at a rate of about 475inches per minute, to deposit the high absorption blocker layer 180 at athickness of about 62 Å. The thus coated substrate is then conveyedthrough four more active coat zones, wherein the outer coat 120 isapplied, as will now be described.

[0093] The substrate 10 is conveyed through a subsequent coat zone thatincludes three sputtering bays each having one zinc target, then througha further coat zone having only one active sputtering bay with a zinctarget, and then through yet another coat zone having three activesputtering bays each with one zinc target. Each of these coat zonescontains an oxidizing atmosphere. A power of about 33-38 kW is appliedto each of the first three zinc targets, a power of about 5 kW isapplied to the fourth zinc target, a power of about 31 kW is applied tothe fifth zinc target, a power of about 37-38 kW is applied to the sixthzinc target, and a power of about 6 kW is applied to the seventh zinctarget. The substrate 10 is conveyed beneath these targets at a rate ofabout 475 inches per minute, while sputtering each target at thedescribed power level, to deposit about 235 Å of zinc oxide directlyover the high absorption blocker layer 180.

[0094] The thus coated substrate is then conveyed into a final coat zonewherein the outermost portion of the transparent dielectric outer coat120 is deposited. This coat zone has two active sputtering bays eachwith a silicon target (doped with aluminum). A nitriding atmosphere ispreferably maintained in this coat zone during sputtering. For example,this atmosphere can be nitrogen at a pressure of about 3.5-5 mbar. Apower of about 3-4 kW is applied to the first silicon target, while apower of about 25-26 kW is applied to the second silicon target. Thesubstrate 10 is conveyed beneath these targets at a rate of about 475inches per minute, while sputtering each target at the described powerlevel, to deposit about 18 Å of silicon nitride directly over theunderlying zinc oxide. This completes the low solar reflectance coating40 of one particular embodiment.

[0095] While preferred embodiments of the present invention have beendescribed, it should be understood that numerous changes, adaptations,and modifications can be made therein without departing from the spiritof the invention and the scope of the appended claims.

What is claimed is:
 1. A pane bearing a low-emissivity coatingcomprising an infrared-reflective layer, a high absorption primarylayer, and a middle coat, said infrared-reflective layer comprisingmaterial that is highly reflective of infrared radiation and having athickness of at least about 175 Å, the high absorption primary layercomprising material that is highly absorptive of solar radiation andhaving a thickness of at least about 100 Å, the middle coat comprisingat least one transparent dielectric film and being positioned betweensaid infrared-reflective layer and the high absorption primary layer. 2.The pane of claim 1 wherein said infrared-reflective layer comprisessilver.
 3. The pane of claim 1 wherein said infrared-reflective layerhas a thickness of between about 182 Å and about 274 Å.
 4. The pane ofclaim 1 wherein a major portion of the thickness of the high absorptionprimary layer is a metallic material.
 5. The pane of claim 1 wherein thehigh absorption primary layer comprises titanium and/or niobium.
 6. Thepane of claim 1 wherein the high absorption primary layer comprises ahighly absorptive dielectric material.
 7. The pane of claim 1 whereinthe high absorption primary layer has a thickness of between about 104 Åand about 151 Å.
 8. The pane of claim 1 wherein the middle coat has anoptical thickness of between about 600 Å and about 872 Å.
 9. The pane ofclaim 8 wherein each film of the middle coat has a refractive index ofbetween about 1.7 and about 2.4.
 10. The pane of claim 1 wherein saidinfrared-reflective layer is positioned further from the substrate thanthe high absorption primary layer.
 11. The pane of claim 1 furthercomprising a high absorption blocker layer deposited over saidinfrared-reflective layer, the high absorption blocker layer comprisingmaterial that is highly absorptive of solar radiation and having athickness of at least about 45 Å.
 12. The pane of claim 11 wherein thehigh absorption blocker layer is deposited directly over saidinfrared-reflective layer.
 13. The pane of claim 11 wherein a majorportion of the thickness of the high absorption blocker layer is ametallic material.
 14. The pane of claim 11 wherein the high absorptionblocker layer comprises titanium and/or niobium.
 15. The pane of claim11 wherein the thickness of the high absorption blocker layer is betweenabout 46 Å and about 78 Å.
 16. The pane of claim 1 wherein thelow-emissivity coating further comprises an inner coat comprising atleast one transparent dielectric film and being positioned between thesubstrate and the high absorption primary layer.
 17. The pane of claim16 wherein the inner coat has an optical thickness of between about 216Å and about 312 Å.
 18. The pane of claim 17 wherein each film of theinner coat has a refractive index of between about 1.7 and about 2.4.19. The pane of claim 1 wherein the low-emissivity coating furthercomprises an outer coat comprising at least one transparent dielectricfilm and being positioned further from the substrate than saidinfrared-reflective layer.
 20. The pane of claim 19 wherein the outercoat has an optical thickness of between about 410 Å and about 582 Å.21. The pane of claim 20 wherein each film in the outer coat has arefractive index of between about 1.7 and about 2.4.
 22. The pane ofclaim 1 wherein the pane is part of an insulating glass unit and thelow-emissivity coating is carried on a #2 surface of the insulatingglass unit.
 23. The pane of claim 22 wherein the insulating glass unithas an exterior solar reflectance of less than about 30%.
 24. The paneof claim 23 wherein the exterior solar reflectance is less than about20%.
 25. The pane of claim 24 wherein the exterior solar reflectance isabout 16%.
 26. The pane of claim 1 wherein the low-emissivity coatinghas an emissivity of less than about 0.07.
 27. The pane of claim 26wherein the emissivity is less than about 0.05.
 28. The pane of claim 27wherein the emissivity is about 0.044.
 29. The pane of claim 22 whereinthe insulating glass unit has an exterior visible reflectance of lessthan about 20%.
 30. The pane of claim 29 wherein the exterior visiblereflectance is less than about 15%.
 31. The pane of claim 30 wherein theexterior visible reflectance is about 11%.
 32. The pane of claim 22wherein the insulating glass unit has a U Value of less than about 0.4.33. The pane of claim 32 wherein the U Value is less than about 0.3. 34.The pane of claim 33 wherein the U Value is about 0.25.
 35. The pane ofclaim 22 wherein the insulating glass unit has a solar heat gaincoefficient of less than about 0.4.
 36. The pane of claim 22 wherein theinsulating glass unit has a transmitted color characterized by an a_(h)color coordinate of between about −1.75 and about −4.5 and a b_(h) colorcoordinate of between about −2 and about −5.
 37. The pane of claim 22wherein the insulating glass unit has an exterior reflected colorcharacterized by an a_(h) color coordinate of between about 1.4 andabout −1.6 and a b_(h) color coordinate of between about 0.5 and about−2.5.
 38. A pane bearing a low-emissivity coating comprising thefollowing sequence of films: a) an inner coat comprising at least onetransparent dielectric film and having an optical thickness of betweenabout 216 Å and about 312 Å; b) a high absorption primary layercomprising material that is highly absorptive of solar radiation andhaving a thickness of least about 100 Å; c) a middle coat comprising atleast one transparent dielectric film and having an optical thickness ofbetween about 600 Å and about 872 Å; d) an infrared-reflective layercomprising material that is highly reflective of infrared radiation andhaving a thickness of at least about 175 Å; e) a high absorption blockerlayer comprising material that is highly absorptive of solar radiationand having a thickness of at least about 45 Å; and f) an outer coatcomprising at least one transparent dielectric film and having anoptical thickness of between about 410 Å and about 582 Å.
 39. A methodof producing coated substrates, the method comprising: a) providing apane having generally-opposed first and second major surfaces; and b)depositing upon one of said major surfaces a low-emissivity coatingcomprising an infrared-reflective layer, a high absorption primarylayer, and a middle coat, said infrared-reflective layer comprisingmaterial that is highly reflective of infrared radiation and having athickness of at least about 175 Å, the high absorption primary layercomprising material that is highly absorptive of solar radiation andhaving a thickness of at least about 100 Å, the middle coat comprisingat least one transparent dielectric film and being positioned betweensaid infrared-reflective layer and the high absorption primary layer.40. The method of claim 39 wherein the method comprises depositing saidinfrared-reflective layer as a silver-containing film.
 41. The method ofclaim 39 wherein the method comprises depositing saidinfrared-reflective layer at a thickness of between about 182 Å andabout 274 Å.
 42. The method of claim 39 wherein the method comprisesdepositing the high absorption primary layer as a metallic film.
 43. Themethod of claim 39 wherein the method comprises depositing the highabsorption primary layer as a titanium and/or niobium containing film.44. The method of claim 39 wherein the method comprises depositing thehigh absorption primary layer as a highly absorptive dielectric film.45. The method of claim 39 wherein the method comprising depositing thehigh absorption primary layer at a thickness of between about 104 Å andabout 151 Å.
 46. The method of claim 39 wherein the method comprisesdepositing the middle coat at an optical thickness of between about 600Å and about 872 Å.
 47. The method of claim 46 wherein the methodcomprises depositing each film of the middle coat as a film having arefractive index of between about 1.7 and about 2.4.
 48. The method ofclaim 39 wherein the method comprises depositing saidinfrared-reflective layer further from the substrate than the highabsorption primary layer.
 49. The method of claim 48 further comprisingdepositing a high absorption blocker layer over said infrared-reflectivelayer, the high absorption blocker layer comprising material that ishighly absorptive of solar radiation and having a thickness of at leastabout 45 Å.
 50. The method of claim 49 wherein the method comprisesdepositing the high absorption blocker layer directly over saidinfrared-reflective layer.
 51. The method of claim 49 wherein the methodcomprises depositing the high absorption blocker layer as a metallicfilm.
 52. The method of claim 49 wherein the method comprises depositingthe high absorption blocker layer as a titanium and/or niobiumcontaining film.
 53. The method of claim 49 wherein the method comprisesdepositing the high absorption blocker layer at a thickness of betweenabout 46 Å and about 78 Å.
 54. The method of claim 39 further comprisingdepositing an inner coat between the substrate and the high absorptionprimary layer, the inner coat comprising at least one transparentdielectric film.
 55. The method of claim 54 wherein the method comprisesdepositing the inner coat at an optical thickness of between about 216 Åand about 312 Å.
 56. The method of claim 55 wherein the method comprisesdepositing each film of the inner coat as a film having a refractiveindex of between about 1.7 and about 2.4.
 57. The method of claim 39further comprising depositing an outer coat further from the substratethan said infrared-reflective layer, the outer coat comprising at leastone transparent dielectric film.
 58. The method of claim 57 wherein themethod comprises depositing the outer coat at an optical thickness ofbetween about 410 Å and about 582 Å.
 59. The method of claim 58 whereinthe method comprises depositing each film of the outer coat as a filmhaving a refractive index of between about 1.7 and about 2.4.